Fuel injector



N. FODOR INJECTOR Jan. 6,' 194s.

Filed Nov. 10, 1942 .Q Smm @x ed forms coming equally enema im; e, 194s UNITED s-'rlafr Es ParitN'il` oFFi/CE ma nunc'ron Nichol maar. wiimet, nl. Application November 1o. isiaseriaino. 465,147

s (ci. a99-4101.16)

The present invention is concerned -with high pressure liquid fuel injectors for internal combustion engines of the Diesel type.

With such injectors best operating results are obtained by initially retarding the rate of delivery of each metered charge and thereafterin-A creasing the rate. Various ways of accomplishing this have been'proposedbut for the most part they have involved machining operations which are extremely dimcult if not impossible to perincreased diameter in front of the bore Il, a

y ,l forwardly'diverging valve seat I8 between the form in quantity production because of the minuteness andA accurate proportioning of certain of the partsv entering into the construction of the nozzle. f l f The purpose of this invention is to provide, in a fuel injector, an improved nozzle which has the above described two-stage operating charl,

acteristic and yet because of the simplicity of-the machining operations required for its design is comparatively easy and inexpensive to manufacture.

Other objects and advantages of the invention will be evident to those skilled in the art upona full understanding ofthe construction,

arrangement and operation of the improvedy nozzle.

one embodiment of the invention is presented.

herein by way of illustration, but it will' of course be understood that the invention is susceptible of being incorporated in other structurally modi'- within the spirit of the invention and the scope of the appended claims.

In the accompanying drawing:

bore I4 and the borey Il. a plurality of ducts I1 (only o ne of which is shown) for delivering fuel to the bore Il, and a third bore I8 of still further increased diameter in front of the bore I5. The passage formed by the bores Il, I5 and I8 is of circular cross section at all points throughout its length and contains a longitudinally recipro- I cable pintle I 8.

The pintie I9'is characterized by a stem 20 The pintie is exposed at its rear end to thepressure of the fuel in the chamber II and is projected Aforwardly by periodic pressure on the fuel whereby 'to unseat the valve 23 and permit discharge of the fuel through the bore I8. The

. bore I8 constitutes the front end of the fuel discharge passage in the nozzle. The pintie I9 is normally maintained in its retracted position,

Fig. 1 is a, greatly enlarged longitudinal section through the front end of an injector, showing a vnozzle constructed in accordance with the invention;

'Fig 2 is astill further enlarged longitudinal f section through the fuel delivery 'passage Vin the nozzle; and

Figs. 3, 4 and 5 are respectively side, front end and rear end views of the nozzle, illustrating the actual size of the same. A

The injector shown in the drawing includes 1a holder I0 which` is adapted to be mounted in the wall of an engine cylinder. The holder I Il with the valve 23l seated, by a helical coil spring ,24. The spring 24 encircles a rearwardly extending tubularportion 25 of the nozzle and is compressed between the rear face 26 of thenozzle and a laterally'separable retaining washer 21 which is positioned in axial abutment with a button-like enlargement 28 on the rear end of the pintie. A

- shim 29. which may be readily replaced by other shims of greater or less thickness, is positioned 'between the yspring 2l and the rear face 26 of the nozzle for effecting any desired adjustment of the pressure controlling the opening of the valve 23. A filter cap 30 of per-forate material contains a fuel chamber II in the front part of the same and a fuel inlet 'passage I2 at'the rear of the chamber, which passage opens axially into the chamber and is adapted to be connected by a conduit with the fuel pump for the particular cylinder with which the injector is used. The holder I0 is open at its front end and is interiorly threaded for the reception nozzle I3 is screwed into the holder, to a point lsubstantially 'flush with the latter, with the nozzle and certain associated parts projecting rearwardly into the chamber II.

of a nozzle I3. ,The-

The nozzle I3 is characterized by anaxial bore' I Il, 'a second relatively short axial bore I5 of surrounds the spring 2l and retaining washer 21, in spaced relation to such parts and also in spaced relation to the walls of the chamber II. The cap 30 is secured at its forward end to the'nozzle I3 in anannular groove 3| formed in lthe latter.

In the operation of the' injector the bore I5 in the nozzle I3 cooperates with the head 2l on the pintie. I8 to provide a very restricted annular y fuel passage about the head during the first part only of the forward movement of 'the pintie, while f the bore I'8 cooperates with the head to provide av comparatively unrestricted annular fuel passage about the head during the remainder of the forward movement. The throttling which occurs duringthe initial part of the stroke is due to the restriction in flow resulting from the presence of the annular step I5 plus the rate of the spring 24. The annularstep I 5 between the valve I8 and the main discharge-bore I8,

4as .0590" in a typical i valve and permit may of course be made shorter or longer with respect to the stroke of the pintle, whereby to correspondingly vary the period in the injection during which the flow is initially throttled. In-Fig. 2 the pintle isAshown in full lines in its retracted position, with the valve 23 seated, and is shown in dotted lines in its forwardly projected position. with the passage about the' head 2l unrestricted. The extent to is projected upon each injection is determined by the thickness of the retaining washer 21. which washer acts as a stop by engaging at its front face with the rear end 32 of the tubular portion 25 of the nozzle.

The nozzle I3 and the pintle I9 are very small parts-the diameter of even the enlarged head 2| on the front end of the pintle being as small injector. The flow restricting bore I5 in an assembly having a head 2l of the above mentioned size would have a diameter somewhere in the neighborhood of .0594"- from which it will be appreciated that the clearance between thebore I5 and the head 2l would be something like .0002" on each side.

To enable the improved nozzle and pintle organization to be easily machined, the bores I4, I5 and I8 in the nozzle are preferably all made cylindrical and cut, with the seat I6, in a single cutting operation. As the multiple-step passage in the nozzle formed by the bores Il, I5 and I8 increases indiameter toward the frontend of the nozzle at every point where` there is any change in diameter, erated'from the front end, permitting the entire nozzle to be made in one piece.

I claim:

1. In a high pressure fuel injector, a nozzle having an axial bore, a second relatively short axial bore of increased diameter immediately in front of the first bore, a forwardly 'diverging valve seat between the rst bore and the second bore,'means for delivering fuel to the 'first bore.' anda third axial bore of still further increased diameter immediately in front of the second bore; a pintle having a stem slidably mounted in the rst bore, a head of increased diameter at the front end of the stem, which head is positioned in the second and third bores in but slightly spaced relation to the second bore and substantially spaced relation to the third bore, an

which the pintle annular groove in the stem adjacent the head for receiving the fuel delivered to the first bore, and a forwardly diverging valve between the groove and the head for engagement with the valve seat; said pintle being projected forwardly by periodic pressure on the fuel to unseat the spring means for normally maintaining the pintle in its retracted position with the valve seated;

the second bore in the nozzle cooperating with the head on the pintle to provide a restricted annular fuel passage about-the head during the the cutting tool can be opmeans for normally retracted positionv with the valve seated; the secsage about the head discharge of the fuel; and

nrst part only of the forward movement of the pintle, and the third bore cooperating with the head to provide a comparatively unrestricted annular fuel passage about the head during the remainder of the forward movement.

2. In a high pressure fuel injector, a nozzle having an axial bore, av second relatively short axial bore of increased diameter immediately in front of the first bore, a forwardly diverging valve seat between the first bore and the second bore, I

means for delivering fuel to the rst bore, and a third axial bore of still further increased diameter immediately in front of the second bQle;

. pintle `having a slidably mounted in the first bore..a head 'of increaseddiameter at the frontend of the stem/which head is positioned in the second and third bores in but slightly spaced relation tothe second bore and substantially spaced relation to thethird bore, an annular groove inthe stem adjacent the head for receiving the fuel delivered to the first bore, and' a forwardly diverging valve between the groove and the head for engagement with the valve seat: said pintle being projected forwardly by periodic pressure on the fuel to unseat the valve and permit discharge of the fuel; and spring maintaining the pintle in its ond bore in the nozzle cooperating with the head on the pintle to provide a restricted annular fuel passage about the head during the first part only of the forward movement of the pintle, and the third bore cooperating with the head to provide a comparatively unrestricted annular-fuel pasduring the remainder ofthe forward movement; the axial passage through the nozzle formed by the first, second and third bores being circular at all points throughout the length of the passage.

-3. In a high pressure fuel injector, a one-piece nozzle having an axial bore, a second relatively short axial bore of increased diameter immediately in front of the first bore, a forwardly diverging valve seat between the first bore and the second bore, means for delivering fuel to the first bore, and a third axial bore of still further increased diameter immediately in front of the second bore;` a pintle having a stem slidabl'y mounted in the first bore, a head of increased diameter at the front end of the stem, which head is positioned in the second and third bores in but slightly spaced relation to the second bore and substantially spaced relation tc the third bore, an annular groove in the stem adjacent the head for receiving the fuel delivered to the first bore, and a forwardly diverging valve between the groove and the head for engagement with the valve seat; said pintle being projected forwardly by periodic pressure on the fuel to unseat the valve and permit discharge of the fuel; and' lspring means for normally maintaining the pinhead to provide a comparatively unrestricted annular fuel passageabout the head duringthe remainder of the forwardl movement; the third bore constituting the front end of the fuel discharge passage in the nozzle.

NICHOLAS ronca.

REFERENCES CITED The following references are of record in the flle of this patent:

lUNI'I'ED STTES PATENTS 

